From: Scott Morris (swm@emanon.com)
Date: Wed Sep 01 2004 - 15:25:27 GMT-3
Actually, the problem lies in the serial interface mechanisms and hardware
queues where multicasts are treated as "pseudo-broadcasts". Which goes out
a higher-priority hardware queue.
NBMA-mode fixes this aspect to. So there are times (HSSI FR link?) where
you may not run into the issue, but nbma-mode is a two-fold item.
Yes, you are correct on the OIL modification for the join/leave concept, but
that has nothing to do with the hardware treatment of the packets/frames.
HTH,
Scott Morris, CCIE4 (R&S/ISP-Dial/Security/Service Provider) #4713, CISSP,
JNCIP, et al.
IPExpert CCIE Program Manager
IPExpert Sr. Technical Instructor
swm@emanon.com/smorris@ipexpert.net
http://www.ipexpert.net
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Brian McGahan
Sent: Wednesday, September 01, 2004 1:52 PM
To: tycampbell@comcast.net; mani poopal; ccielab@groupstudy.com
Subject: RE: ip pim nbma mode/auto rp/dense mode
>This tells me that if you want the neighbors in NBMA Mode (which
>includes frame-relay) to receive multicast packets, then you must
>enable ip pim nbma mode in a sparse mode environment across the NBMA
>network
Not true. It is an optimization, not a requirement. By default,
the outgoing interface list for a multicast group uses the interface itself
for transmission. In the case of an NBMA interface, a broadcast packet is
sent as a replicated unicast out all circuits configured for broadcast
support for the specified protocol. With PIM NBMA mode, the OIL is modified
to direct traffic to a specific endpoint of the network, and not the
interface itself. This results in broadcast replication only to neighbors
that have explicitly joined the group.
> q2 response from Brian I agree with, I didn't say you couldn't use it,
> just doesn't seem necessary...at least in a lab environmant
What do you mean that it doesn't seem necessary?
> q3 response from Brian I agree with also, but I was only looking at
> the announce - discovery aspect of auto-rp
That is what I'm referring to. It is not a requirement to run
sparse-dense mode to receive traffic for the 224.0.1.39 and 224.0.1.40
groups. You can either manually specify an RP for these groups, or run
auto-rp listener. The manual specification would be like follows:
Access-list 1 permit 224.0.1.39
Access-list 1 permit 224.0.1.40
!
Ip pim rp-address 1.2.3.4 1
HTH,
Brian McGahan, CCIE #8593
bmcgahan@internetworkexpert.com
Internetwork Expert, Inc.
http://www.InternetworkExpert.com
Toll Free: 877-224-8987 x 705
Outside US: 775-826-4344 x 705
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Live Chat: http://www.internetworkexpert.com/chat/
________________________________________
From: tycampbell@comcast.net [mailto:tycampbell@comcast.net]
Sent: Wednesday, September 01, 2004 12:37 PM
To: Brian McGahan; mani poopal; ccielab@groupstudy.com
Subject: RE: ip pim nbma mode/auto rp/dense mode
Q1 reply
Enabling PIM Nonbroadcast Multiaccess Mode PIM nonbroadcast multiaccess
(NBMA) mode allows the Cisco IOS software to replicate packets for each
neighbor on the NBMA network. Traditionally, the software replicates
multicast and broadcast packets to all "broadcast" configured neighbors.
This action might be inefficient when not all neighbors want packets for
certain multicast groups. NBMA mode enables you to reduce bandwidth on links
leading into the NBMA network, and to reduce the number of CPU cycles in
switches and attached neighbors.
This tells me that if you want the neighbors in NBMA Mode (which includes
frame-relay) to receive multicast packets, then you must enable ip pim nbma
mode in a sparse mode environment across the NBMA network
q2 response from Brian I agree with, I didn't say you couldn't use it, just
doesn't seem necessary...at least in a lab environmant
q3 response from Brian I agree with also, but I was only looking at the
announce - discovery aspect of auto-rp
-------------- Original message --------------
> > > (Q1)Guys do we have to use ip pim nbma command on multicast over
> frame
> > cloud.
> > yes, but only on the hub router of the frame-relay cloud, not on
> the
> > spokes
>
> No it is not required. NBMA mode is simply an optimization of join
> processing, leave processing, and transmission of multicast packets
> over NBMA.
>
> > > (Q2)Is this command only works with sparse mode or will it works
> with
> > sparse
> > > dese mode too.
> > not really necessary to use it for sparse-dense mode
>
> Yes you can use it for sparse-dense mode. It will however only affect
> groups running in sparse-mode.
>
> > > (Q3)If you use auto-rp, you need a dense mode component(sparse
> > > dense
> > mode) for rp candidate to talk to mapping agent. When mapping agent
> is
> > configured on the hub router(of NBMA) and if RP candidates are
> configured
> > on the spokes what is the pim mode to configure on the frame
> > cloud(Do
> we
> > have to create a loopback on the rp candidate and enable
> > sparse-dense
> > mode)
> > if you are using auto-rp, you will need to use sparse-dense mode
> > over
> the
> > frame-cloud. You do not have to create a loopback, you can use an
> Ethernet
> > interface, but you must enable sparse-dense mode on the Ethernet
> > interface. If you do create a loopback interface, you should enable
> > sparse-dense mode on that interface
>
> You don't necessarily need to run sparse-dense mode with auto-rp. You
> can statically define a default RP for the auto-rp groups, or you can
> run auto-rp listener.
>
> Brian McGahan, CCIE #8593
> bmcgahan@internetworkexpert.com
>
> Internetwork Expert, Inc.
> http://www.InternetworkExpert.com
> Toll Free: 877-224-8987 x 705
> Outside US: 775-826-4344 x 705
> 24/7 Support: http://forum.internetworkexpert.com
> Live Chat: http://www.internetworkexpert.com/chat/
>
>
> > -----Original Message-----
> > From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf
> Of
> > tycampbell@comcast.net
> > Sent: Wednesday, September 01, 2004 10:39 AM
> > To: mani poopal; ccielab@groupstudy.com
> > Subject: Re: ip pim nbma mode/auto rp/dense mode
> >
> > > (Q1)Guys do we have to use ip pim nbma command on multicast over
> frame
> > cloud.
> > yes, but only on the hub router of the frame-relay cloud, not on
> the
> > spokes
> >
> > > (Q2)Is this command only works with sparse mode or will it works
> with
> > sparse
> > > dese mode too.
> > not really necessary to use it for sparse-dense mode
> >
> > > (Q3)If you use auto-rp, you need a dense mode component(sparse
> > > dense
> > mode) for rp candidate to talk to mapping agent. When mapping agent
> is
> > configured on the hub router(of NBMA) and if RP candidates are
> configured
> > on the spokes what is the pim mode to configure on the frame
> > cloud(Do
> we
> > have to create a loopback on the rp candidate and enable
> > sparse-dense
> > mode)
> > if you are using auto-rp, you will need to use sparse-dense mode
> > over
> the
> > frame-cloud. You do not have to create a loopback, you can use an
> Ethernet
> > interface, but you must enable sparse-dense mode on the Ethernet
> > interface. If you do create a loopback interface, you should enable
> > sparse-dense mode on that interface
> >
> > > (Q4.)What is the easiest way do determine that we need static
> > > mroute
> > command on the multicast routers.
> > Watch for the RPF check, make sure that the multicast traffic is
> flowing
> > in the direction that you want it to.If it is not, then you should
> > use
> an
> > mroute
> >
> > HTH! :-)
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> > -------------- Original message --------------
> >
> > > Hi Group,
> > >
> > > I am reading Williams Multicast book and has some questions
> > >
> > > "ip pim nbma mode only support pim sparse mode, and dense mode
> > > will
> not
> > work
> > > properly on P2M NBMA networks(Frame Relay)"
> > >
> > > (Q1)Guys do we have to use ip pim nbma command on multicast over
> frame
> > cloud.
> > > (Q2)Is this command only works with sparse mode or will it works
> with
> > sparse
> > > dese mode too.
> > > (Q3)If you use auto-rp, you need a dense mode component(sparse
> > > dense
> > mode) for
> > > rp candidate to talk to mapping agent. When mapping agent is
> configured
> > on the
> > > hub router(of NBMA) and if RP candidates are configured on the
> spokes
> > what is
> > > the pim mode to configure on the frame cloud(Do we have to create
> > > a
> > loopback on
> > > the rp candidate and enable sparse-dense mode) In the above
> > > situation, can we configure sparse mode on the frame
> > cloud(serial
> > > interfaces) and sparse dense mode on the loop back interface of RP
> > candidate.
> > > (Q4.)What is the easiest way do determine that we need static
> > > mroute
> > command on
> > > the multicast routers.
> > >
> > > group sorry for long list of questions. Answers from group experts
> are
> > > appreciated
> > >
> > > thanks
> > >
> > > Mani
> > >
> > >
> > > B.ENG,A+,CCNA,CCNP,CCNP-VOICE, CSS1,CNA,MCSE
> > > (416)431 9929
> > > MANI_CCIE@YAHOO.COM
> > >
> > > --------------------------------- Do you Yahoo!?
> > > Yahoo! Mail - Helps protect you from nasty viruses.
> > >
> > >
> ______________________________________________________________________
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